Question

explain Haworth synthesis of anthracene

Answer 1

Answer:

Naphthalene is an organic compound with formula  C10H8. It is the simplest polycyclic aromatic hydrocarbon and a white crystalline solid with a characteristic odour that is detectable at concentrations as low as 0.08 ppm by mass.

As an aromatic hydrocarbon, naphthalene's structure consists of a fused pair of benzene rings. It is best known as the main ingredient of traditional mothballs.

It can be synthesized by Haworth synthesis, the steps are as follows:

1. The Friedel craft acylation reaction of benzene with succinic anhydride gives 3 benzoylpropionic acid. 

2. Next is the Clemmenson’s reaction with  3-benzoylpropionic acid which gives 4-phenylebutanoic acid.

3. On heating this product in the presence of conc. sulfuric acid results in the formation of ring structure of α-tetralene by the ellimination of water molecule. 

4. The Clemmenson reaction of α-tetralene gives tetrahydronaphthalene.

5. Dehydrogenation of tetrahydronaphthalene in the presence of selenium yields naphthalene.

Explanation:

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Answer 2

Anthracene, phenanthrene, and other aromatic compounds can also be made via Haworth synthesis.

Haworth synthesis:

• The Friedel-Crafts acylation of naphthalenes with succinic anhydride, followed by a Clemmensen reduction or Wolff-Kishner reduction, cyclization, reduction, and dehydrogenation, is known as the Haworth synthesis.
• Haworth synthesis can be used to create it; the procedures are as follows:
• Succinic anhydride and benzene undergo a Friedel-Craft acylation process, resulting in 3 benzoylpropionic acid.
• The second step produces 4-phenylebutanoic acid through the Clemmenson reaction with 3-benzoylpropionic acid.
• The so-called Elbs reaction, which involves the cyclodehydration of o-methyl- or o-methylene-substituted diarylketones, is a well-known laboratory procedure for producing anthracene.

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